Use relative path for SCRIPTDIR (#22598)
Use relative path for SCRIPTDIR (#22598)

Summary:
Fixes https://github.com/facebook/react-native/issues/22521

The current approach has an issue with white spaces when compiling in Xcode 10.1

![space](https://user-images.githubusercontent.com/615282/49782648-07836f80-fd52-11e8-952f-b93f8c593c60.png)

Change back to relative path fixes this issue
Pull Request resolved: https://github.com/facebook/react-native/pull/22598

Differential Revision: D13421446

Pulled By: hramos

fbshipit-source-id: 688157b2e951399059cb6c95e2a6ce8d176e9b9c

pandiaraj44/react-native,hoangpham95/react-native,pandiaraj44/react-native,hammerandchisel/react-native,exponentjs/react-native,hammerandchisel/react-native,arthuralee/react-native,hammerandchisel/react-native,myntra/react-native,facebook/react-native,javache/react-native,janicduplessis/react-native,myntra/react-native,hammerandchisel/react-native,janicduplessis/react-native,arthuralee/react-native,janicduplessis/react-native,exponent/react-native,exponentjs/react-native,janicduplessis/react-native,myntra/react-native,javache/react-native,hammerandchisel/react-native,exponent/react-native,arthuralee/react-native,exponentjs/react-native,pandiaraj44/react-native,javache/react-native,myntra/react-native,facebook/react-native,facebook/react-native,hoangpham95/react-native,exponentjs/react-native,facebook/react-native,arthuralee/react-native,arthuralee/react-native,facebook/react-native,pandiaraj44/react-native,javache/react-native,facebook/react-native,janicduplessis/react-native,janicduplessis/react-native,janicduplessis/react-native,exponentjs/react-native,javache/react-native,exponentjs/react-native,myntra/react-native,exponent/react-native,exponent/react-native,hoangpham95/react-native,exponent/react-native,exponent/react-native,javache/react-native,hammerandchisel/react-native,hammerandchisel/react-native,javache/react-native,pandiaraj44/react-native,javache/react-native,hammerandchisel/react-native,hoangpham95/react-native,hoangpham95/react-native,pandiaraj44/react-native,exponentjs/react-native,facebook/react-native,myntra/react-native,hoangpham95/react-native,facebook/react-native,javache/react-native,myntra/react-native,hoangpham95/react-native,exponentjs/react-native,hoangpham95/react-native,facebook/react-native,exponent/react-native,pandiaraj44/react-native,pandiaraj44/react-native,myntra/react-native,janicduplessis/react-native,exponent/react-native,myntra/react-native